Special Meeting Coverage: Heart Rhythm Society 2012

From the Heart Rhythm Society’s 33rd Annual Scientific Sessions: radiofrequency catheter ablation beats antiarrhythmic drugs in patients with paroxysmal AF, apixaban reduces risk of stroke and systemic embolism more than warfarin across the AF spectrum, and researchers find that waist-to-hip ratio better predicts sudden cardiac death than BMI.

RAAFT-2: Catheter Ablation With PVI Burns AADs as First-Line for Paroxysmal AF

Boston—Radiofrequency (RF) catheter ablation with pulmonary vein isolation (PVI) was superior to antiarrythmic drugs (AADs) in extending the time to first recurrence of atrial dysrhythmia in patients with paroxysmal AF. The interventional option also reduced the frequency of symptomatic and asymptomatic AF, atrial flutter, and atrial tachyarrhythmia.

“These findings support the indication of RF PVI as first-line therapy in patients with paroxysmal AF,” said Carlos Morillo, MD, Hamilton Health Sciences-McMaster University in Ontario. The trial results were presented during a Late-Breaking Clinical Trial session at the Heart Rhythm Society’s 33rd Annual Scientific Sessions.

The RAAFT-2 (Radiofrequency Ablation vs. Anti-arrhythmic Drugs as First-Line Treatment of Symptomatic Atrial Fibrillation) trial was designed to assess whether RF catheter-based PVI is superior to AADs as first-line therapy in 127 patients with symptomatic paroxysmal recurrent AF not previously treated with therapeutic doses of AADs.

The majority (>97%) of patients in the study had paroxysmal AF, with less than 3% presenting with persistent AF. Patients were also highly symptomatic, with those in the ablation arm experiencing, for example, 47.7 episodes of AF in the 6 months prior to enrollment. About 43% of study participants had undergone previous electrical cardioversion.

Follow-up continued for 2 years, a longer period than typical for an AF study on catheter ablation.
The primary efficacy outcome was the time to first recurrence of symptomatic or asymptomatic AF, atrial flutter, or atrial tachyarrhythmia documented clinically using 12-lead ECG, rhythm strip, or transtelephonic monitoring (TTM) recording.

At 2 years, the recurrence rate was 55% in the catheter ablation arm compared to 72% of the AAD arm, resulting in a significant 44% reduction in risk of recurrence with RF PVI (p = 0.02).

Serious complications were reported in 19.7% of the AAD group and in 7.7% of the ablation group. These post-ablation complications included cardiac tamponade (6.2%) and severe pulmonary vein stenosis (1.5%). There were no reports of atrio-esophageal fistula, thromboembolism related to the procedure, or phrenic nerve injury. In the AAD arm, complications included syncope (3.3%), 1:1 atrial flutter (1.6%), or another significant adverse event that led to drug discontinuation (14.3%). No deaths were reported in either group.

According Dr. Morillo, the study results are potentially practice changing. “We believe our findings are significant enough to point to a change in how we treat patients who have not yet received treatment for symptomatic AF. The analysis revealed that a higher rate of adverse events occur in patients that begin AADs first, which is currently the recommended first-line treatment practice. Our trial showed that ablation is superior in the real world, and is a more effective and safer course of first-line treatment with less patient complications.”

ARISTOTLE: Apixaban Reduces Stroke Risk Across the AF Spectrum

Boston—Apixaban reduced the risk of stroke or systemic embolism compared to warfarin in patients enrolled in the ARISTOTLE trial whether they presented with paroxysmal, persistent, or permanent AF.
As tested in 18,201 patients with AF and at least one additional risk factor for stroke, the direct factor Xa inhibitor was superior to warfarin at reducing stroke and systemic embolism, bleeding and death. In this prespecified secondary analysis, the investigators tested for a differential effect for apixaban in individuals with paroxysmal (15.3%) and persistent or permanent AF (84.7%).

Sana Al-Khatib, MD, of the Duke Clinical Research Institute, Duke University in Durham, North Carolina, presented the results during a Late-Breaking Clinical Trial session at Heart Rhythm Society 2012 Scientific Sessions.

Contrary to previous studies suggesting a similar stroke risk for all types of AF, ARISTOTLE participants with persistent or permanent AF had a higher rate of stroke or systemic embolism (3.5% vs. 2.2%; p = 0.002) and all-cause death (9.4% vs. 7.5%; p < 0.0001), compared to those with paroxysmal AF. Importantly, the investigators found a consistent reduction in stroke or systemic embolism (p = 0.71 for interaction), all-cause death (p = 0.75 for interaction) and major bleeding (p = 0.50 for interaction) with apixaban compared with warfarin for both AF types.

Apixaban (Eliquis, Pfizer/Bristol-Myers Squibb) is not yet approved for any indication in the United States. The FDA is scheduled to make a decision on apixaban for the AF indication on June 28, 2012. The agent was approved in May 2011 in the European Union for the prevention of venous thromboembolism in patients who have undergone elective hip- or knee-replacement surgery.

ARIC: Waist-to-Hip Ratio Better Indicator for Sudden Cardiac Death Risk than BMI

Boston—Research presented at the Heart Rhythm Society Scientific Sessions in Boston suggested that the waist-to-hip ratio is a more significant indicator of the risk of suffering sudden cardiac death than body mass index (BMI).

An analysis of the Atherosclerosis Risk in Communities (ARIC) study cohort, which includes 15,156 subjects, indicated that in 301 incidences of sudden cardiac death (SCD) over 12 years of follow-up, BMI, waist circumference, and waist-to-hip ratio all correlated positively with SCD. However, after adjusting for diabetes, LDL levels, hypertension, prevalent coronary heart disease, HF, and left ventricular hypertrophy, only waist-to-hip ratio was significantly associated with SCD (p = 0.009 for trend).

Lead study author Selcuk Adabag, MD, MS, a professor of medicine at the University of Minnesota in Minneapolis, noted that the key significant finding was that abdominal obesity “was an independent risk factor for SCD,” even after accounting and adjusting for other factors such as diabetes, hypertension and CHD. He added that “physicians should make obesity prevention and treatment a priority to reduce the risk of coronary disease as well as SCD.”

ASSERT: Genetic, Environmental Factors May Affect Development of AF

Boston—New research presented at Heart Rhythm 2012 suggested that the incidence of atrial fibrillation in a large population may be influenced by genetic factors, environmental factors or both.

Researchers for the Asymptomatic AF and Stroke Evaluation in Pacemaker Patients and the AF Reduction Atrial Pacing (ASSERT) Trial enrolled 2,580 patients in North America, Asia, and Europe. Self-reported data on race was included (European, n = 1,900; Chinese, n = 89; Japanese, n = 105; Black African, n = 73). All patients in the study had dual-chamber pacemakers that enabled continuous monitoring of AF free of ascertainment bias.

At 2.5 years follow-up, Chinese (10.1%; p = 0.056 for comparison) and Black African (9.5%; p = 0.026 for comparison) patients had lower incidence of AF lasting longer than 6 hours when compared with their European counterparts (18.0%), and the difference persisted even after adjusting for baseline risk factors for AF. Interestingly, Black African patients maintained this difference, despite having more risk factors for AF than European patients.

Lead author Chu-Pak Lau, MD, from the University of Hong Kong, said that ASSERT study results have “implications for underlying genetic differences,” as well as therapeutic targets for the prevention of AF. “It opens the breadth of research opportunities to identify the cause of susceptibility, with a view to develop drugs or targets for therapy,” he said.

Keywords: Hypertrophy, Left Ventricular, Obesity, Abdominal, Follow-Up Studies, Pulmonary Veins, Coronary Disease, Syncope, Venous Thromboembolism, Risk Factors, Electrocardiography, Waist Circumference, Waist-Hip Ratio, Phrenic Nerve, Esophageal Fistula, Factor Xa, Pyridones, Hypertension, Death, Sudden, Cardiac, United States, Stroke, Atherosclerosis, Electric Countershock, Pyrazoles, Constriction, Pathologic, Tachycardia, Incidence, Body Mass Index, Catheter Ablation, Diabetes Mellitus, Cardiac Tamponade, Atrial Flutter

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